CN115715264A

CN115715264A - Electronic control unit and electric power steering system

Info

Publication number: CN115715264A
Application number: CN202080102135.2A
Authority: CN
Inventors: M·洛克斯坦; B·达泽恩伯格
Original assignee: Hella GmbH and Co KGaA
Current assignee: Hella GmbH and Co KGaA
Priority date: 2020-05-08
Filing date: 2020-05-08
Publication date: 2023-02-24
Also published as: WO2021223876A1; EP4146523A1; US20230067790A1

Abstract

The invention relates to an electronic control unit (100) for an electric power steering system (200), the electric power steering system (200) comprising a housing (210) and an electric motor, the electronic control unit (100) being configured to be arranged inside the housing (210) and electrically connected to the electric motor, wherein the electronic control unit (100) comprises at least one power supply board (30, 40) and a heat sink (50), the at least one power supply board (30, 40) being attached to the heat sink (50), and whereby a heat sink edge (59) of the heat sink (50) comprises a slot (51) arranged for crimping the housing (210) into the slot (51) and thereby fixing the heat sink (50) with the housing (210). The invention further relates to an electric power steering system (200).

Description

Electronic control unit and electric power steering system

Technical Field

The present invention relates to an electronic control unit for an electric power steering system and an electric power steering system.

Background

In an electric power steering system, the electronic control unit may be connected to an electric motor for supplying power thereto from a power source such as a battery. The electric power steering system may assist a driver or a machine in an autonomous vehicle in performing a handling operation (typically steering) on a transport device. The transportation device may be an automobile.

The electric power steering system may further include a torque sensor, a steering shaft, a handle (typically a steering wheel), and a power source. Hereinafter, a typical arrangement and operation of an electric power steering apparatus in an automobile will be described.

The torque sensor may be mounted on the steering shaft. The torque sensor detects a torque applied to the steering shaft by operating the handle when the steering shaft is rotated by operating the handle. When the torque sensor detects the torque, a torque signal is output from the torque sensor to the electronic control unit. The electronic control unit then drives the electric motor based at least on the torque signal. Alternatively, the control means may contain further data, such as vehicle speed, in addition to the torque signal for controlling the driving of the electric motor.

The electronic control unit drives the electric motor by supplying a drive current to the electric motor from a power source such as a battery of an automobile. Then, according to the configuration in the automobile, the driving force generated from the electric motor is transmitted to the wheels directly or via the gear box. Therefore, the electric power steering apparatus changes the steering angle of the wheels by amplifying the torque of the steering shaft by means of the electric motor. This enables the driver to operate the handle with less force.

The electronic control unit includes a power strip electrically connected to the electric motor. Transmitting power to the electric motor via the power strip. Whereby, during operation of the electronic control unit, the power strip generates heat. In order to prevent overheating and damage to the electronic control unit, a heat sink may be provided inside the electronic control unit and arranged in thermal contact with the housing of the electric power steering system or the electric motor.

DE 10 2007 014 645 A1 describes an electrical assembly for an electric power steering system of a motor vehicle. The electric motor is arranged within a tubular housing made of a heat conductive material, with an electronic control unit for controlling the electric motor and a heat sink connected to the housing of the electric motor for dissipating heat from a power component. The heat sink is inserted into the tubular housing, the heat sink having a radial edge and the radial edge having a diameter corresponding in size to an inner diameter of the tubular housing.

In known configurations of the heat sink inside the housing, heat generated by a power supply board inside the electronic control unit may be dissipated through the housing of the electric power steering system or the electric motor. However, it is desirable to further improve the heat radiation characteristics of the electronic control unit at low manufacturing costs of the electronic control unit and the electric power steering system.

Disclosure of Invention

It is therefore an object of the present invention to improve the electronic control unit for an electric power steering system and the electric power steering system known in the art, and in particular to provide an electronic control unit for an electric power steering system and an electric power steering system with improved heat dissipation characteristics, which are also easy to assemble and have low manufacturing costs.

This problem is solved by the claims. This object is therefore solved by an electronic control unit according to independent claim 1 and an electric power steering system according to dependent claim 15. Further details of the invention emerge from the dependent claims 2 to 14 as well as from the description and the drawings. Thus, the features and details described in connection with the electronic control unit of the invention apply to the electric power steering system and vice versa, so that they are or can be mutually referenced in relation to the disclosure of the various aspects of the invention.

According to a first aspect of the present invention, the problem is solved by an electronic control unit for an electric power steering system comprising a housing and an electric motor, the electronic control unit being configured to be arranged inside the housing and electrically connected to the electric motor, whereby the electronic control unit comprises at least one power supply board and a heat sink, the at least one power supply board being attached to the heat sink, and whereby at least one peripheral outer surface of a heat sink edge of the heat sink is in direct contact with an inner surface of the housing, such that heat generated by the at least one power supply board is conducted to the housing via the heat sink.

Heat generated in the operation of the electronic control unit can be efficiently transferred to the inner surface of the case along the outside of the periphery of the heat sink edge of the heat sink. Accordingly, heat is transferred from the inside of the electronic control unit that generates heat to the housing. The housing may have a much larger surface than the heat sink itself. Thus, heat transferred to the heat sink can be dissipated more quickly and more easily at the housing. Further, for example, the housing may be efficiently cooled by ambient air.

In particular, the outer diameter of the peripheral outer surface of the heat sink rim may be equal or substantially equal to the inner diameter of the inner surface of the housing. Substantially containing deviations that are mathematically exactly equal for technical reasons such as manufacturing accuracy. Therefore, the peripheral outer surface is in close contact with the housing, so that heat generated in the at least one power supply board can be efficiently transferred to the housing via the heat sink.

The electric motor may in particular be arranged inside the housing. The housing can in particular be an electric motor housing, i.e. a housing of the electric motor. The housing may in particular have a tubular shape. The housing may also in particular have a circular or oval cross section. Also, the housing may be made of a thermally conductive material. The thermally conductive material may in particular be or comprise a metal such as aluminium, magnesium, copper or similar materials.

The at least one power strip may be mounted to the heat sink. The at least one power strip may be surrounded by the heat sink rim. The at least one power strip may in particular be provided as a printed circuit board. The at least one power strip may comprise electronic components, such as coils and capacitors, for enabling the power strip to transfer power from a power source to the electric motor.

The electronic control unit may further comprise a logic board. The logic board may in particular be provided as a printed circuit board. The logic board does not have to be attached to the heat sink. In particular, the logic board may not be attached to the heat sink. In operation of the electronic control unit, the logic board generates less heat than the at least one power board, and therefore it may be prioritized to attach at least one power board, which generates more heat in operation of the electronic control unit, to the heat sink.

In addition, the electronic control unit may further include a connector board. For example, the connector plate may be made of plastic. The connector plate may be formed as a cap for sealing the housing at one end thereof. The connector board may be provided with a seal for sealing the interior of the housing with respect to the exterior. The seal may be made of silicone rubber. The connector board may comprise one, two, three or more connectors, in particular plug connectors. At or inside the plug connector, the connector board may be provided with electrical contacts. The electrical contacts may be made of, for example, a copper alloy to provide large electrical conductivity. One or more of the plug connectors may be configured to contact a control board of the transport device with the logic board. Thereby, the torque sensor, other sensors and/or other electronic control units may be connected to the logic board. The plug connectors may be connected to the at least one power strip by power connectors.

It may be that the heat sink comprises a slot arranged for crimping the housing into the slot and thereby securing the heat sink and the housing together.

When the housing is pressed into the groove of the heat sink, a particularly tight fit of the heat sink inside the housing is achieved and the thermal conductivity from the heat sink to the housing can also be improved. The groove arranged for crimping the housing into the groove may thus also be configured for thermally connecting the heat sink with the housing thereby. In addition, the total contact surface of the heat sink with the housing and thus the total thermal conductivity from the heat sink to the housing is improved even further. Furthermore, providing the heat sink with the slot may be performed at relatively low cost when manufacturing the heat sink, and crimping the housing into the slot is a relatively simple, fast and cost-effective way of fixing the heat sink and the housing of the electric power steering system together, in particular throughout the electronic control unit.

The crimping may be performed by pressing the housing into the groove at the outside of the housing. Thereby, the housing is plastically deformed and brought into contact with the heat sink at the groove of the heat sink. The groove may have, for example, a rectangular, U-shaped or V-shaped shape. Additionally, more than one slot may be provided in the heat sink to crimp it with the housing. For example, the heat sink edge of the heat sink may comprise at least two slots for crimping the housing into the at least two slots.

It is possible that the groove is a circumferential groove such that it is arranged around at least half of the circumference of the heat sink edge of the heat sink, preferably around the entire circumference of the heat sink. In this way, a particularly simple crimping can be carried out around the edge of the heat sink and the periphery of the housing, and a particularly secure connection of the heat sink to the housing can be achieved.

Further, it is possible that the groove is arranged between two peripheral outer surfaces of the heat sink rim, thereby directly connecting the heat sink and the housing. Thereby, the housing may be crimped into the slot between two peripheral outer surfaces of the heat sink rim such that the housing is crimped between the two peripheral outer surfaces. This provides a particularly secure connection of the heat sink to the housing. In particular, the outer diameter of the two peripheral outer surfaces of the heat sink rim may be equal or substantially equal to the inner diameter of the inner surface of the housing. Substantially containing deviations that are mathematically exactly equal for technical reasons such as manufacturing accuracy. Therefore, the two peripheral outer surfaces are in close contact with the housing, so that heat generated in the at least one power supply board can be efficiently transferred to the housing via the heat sink.

Further, it is possible that the crimp housing thermally connects the heat sink with the housing at the slot. Therefore, the heat conduction from the heat sink to the housing can be improved.

It is also possible that the electronic control unit includes a first power supply plate and a second power supply plate as the at least one power supply plate, the heat sink being sandwiched between the first power supply plate and the second power supply plate. The first and second power strips may each be provided as redundant power strips for powering the electric motor independently of each other. Both the first power strip and the second power strip may be arranged such that each has three phases of electricity to supply the electric motor with three phases of electricity. Thus, the first and second power strips may be arranged together to supply six phases of electricity for the electric motor. The first power supply plate may be disposed on one side of the heat sink, and the second power supply plate may be disposed on the other side of the heat sink. The first and second power strips may be directly attached to the heat sink with their circuit boards and electronic components. Thermal interface materials may be disposed between the first power strip and the heat sink and between the second power strip and the heat sink to thermally attach the respective components to one another for better thermal conductivity.

It is also possible that the electronic components of the first power supply board and the electronic components of the second power supply board face the heat sink. Further, it may be provided that the electronic component extends towards the heat sink. In particular, it can be provided that the electronic component extends at least partially inside the heat sink.

Furthermore, it is possible that the heat sink is configured as an at least partially circular heat sink plate. In particular, the heat sink may be an at least semi-circular heat sink plate or a complete circular heat sink plate. The heat sink edge of the heat sink may have or define a circular form of the heat sink plate. The heat sink may be a flat plate in the sense that the thickness of the heat sink is smaller than its diameter or radius.

Further, it is possible that the heat sink comprises several heat conducting surfaces arranged in contact with electronic components of the at least one power strip. A thermal interface material may be disposed between the electronic component and the thermally conductive surface. Thereby, the heat generated by the electronic component can be conducted very efficiently to the heat sink.

Thereby, it is possible that the several heat conducting surfaces are arranged at different heights along the thickness of the heat sink to accommodate electronic components of different heights. Thereby, design freedom of the at least one power strip in terms of its specific electronic components (such as their size and geometry) may be maintained, while still enabling a high thermal conductivity of the at least one power strip to the heat sink. In other words, the heat sink may be adapted in its form and geometry to the at least one power strip, not vice versa.

It is also possible that the heat sink comprises a heat sink through hole and that at least one of the at least one power supply board is fixed to the heat sink by a bolt which passes through the heat sink through hole and is fastened in a ridge extending from a connector board of the electronic control unit. This enables a simple and reliable and detachable connection of the at least one power supply board with the heat sink and further with the connector board. Also, by arranging the logic board of the electronic control unit between the at least one power board and the connector board, the logic board of the electronic control unit can thereby be sandwiched and easily fixed between the at least one power board and the connector board.

Alternatively or additionally, it is possible that the heat sink comprises a heat sink hole and at least one of the at least one power strip is fixed to the heat sink by a bolt fastened in the heat sink hole. Thereby, a simple and reliable and detachable connection between the at least one power supply board and the heat sink is provided.

In particular, when a first power strip and a second power strip of the at least one power strip are provided, the first power strip may be attached through the heat sink through hole and the bump in the connector plate, and the second power strip may be attached through the hole in the heat sink. This provides particularly good maintainability, since the second power strip can be replaced without detaching the first power strip from the heat sink, and further improves the reliability of the secure connection.

Further, it is possible that the heat sink comprises a heat sink recess for a second power connector of the electronic control unit, the second power connector extending from a connector board of the electronic control unit to at least one power board of the at least one power board through the heat sink recess inside the heat sink. These second power connectors may be used to transfer current from a connector board, which may be connected to the power source, to the at least one power board. The heat sink recess allows for a simple and cost-effective design of the heat sink and the second power connector. The heat sink recess may be designed as a flat slot. The second power connector may be designed as a second power cable or as a second power lug. The second power connector may have a flat shape and/or a rectangular shape.

The term "second" in the second power connector does not imply that the first power connector must also be present. However, in a configuration having two power strips (a first power strip and a second power strip of the at least one power strip), a first power connector for connecting with the first power strip may be provided. Then, the second power connector is connected to the second power board. Thus, each of the two power strips may be individually supplied with current for transmitting the current as a driving current to the electric motor.

It is also possible that the heat sink comprises a heat sink cut-out extending in particular from an edge of the heat sink to an interior of the heat sink, through which a second logic connector extends from a logic board of the electronic control unit to at least one of the at least one power board. The heat sink cutouts may have a partially circular shape and/or a partially flat shape. The heat sink cut-out allows for a simple and cost-effective design of the heat sink and the second logic connector.

The term "second" in said second logical connector does not mean that the first logical connector must also be present. However, in a configuration having two power supply boards (a first power supply board and a second power supply board of the at least one power supply board), a first logic connector for connecting the logic board with the first power supply board may be provided. The second logical connector may then be connected to the second power strip. Thus, each of the two power strips may be separately provided with signals or instructions from the logic board for transmitting drive current to the electric motor.

It is thus possible that a first electric motor connector from a power strip of the at least one power strip extends through the heat sink cutout for connection with an electric motor of the electric power steering system. Therefore, the number of cutouts or grooves can be reduced, and the electronic control unit can have a compact design. By means of the first electric motor connector, a driving current from a power strip of the at least one power strip may be transmitted along the electronic control unit to the electric motor via the heat sink.

Also, the term "first" in the first electric motor connector does not mean that the second electric motor connector must also be present. However, in the configuration having two power supply boards (the first power supply board and the second power supply board of the at least one power supply board), a second electric motor for connecting the second power supply board with the electric motor may be provided. The first electric motor connector may then be connected to the first power strip. Thereby, each of the two power supply boards can individually transmit the driving current to the electric motor.

Further, it is possible that the heat sink comprises a heat sink protrusion protruding from the heat sink beyond the at least one power supply board and arranged to be placed on an inner edge of an interior of a housing of the electric power steering system. By means of the heat sink projection, when the electronic control unit is mounted in the housing, the end position of the electronic control unit in the housing can be easily detected. The end position is achieved when the projection rests on an inner edge inside the housing, and the electronic control unit cannot be pushed further into the housing without using excessive force to bend or damage the projection. Thereby, a defined position is provided where the housing is crimped into the groove, and each time the heat sink is engaged with the housing, the crimping can be performed at the defined position, thereby facilitating manufacturing.

According to a second aspect of the invention, the problem set forth in the introduction of the present description is solved by an electric power steering system comprising an electronic control unit according to the first aspect of the invention, wherein an electric motor of the electric power steering system is electrically connected to the at least one power supply board by means of at least one electric motor connector, and whereby a housing of the electric power steering system is crimped into a slot of a heat sink of the electronic control unit.

In a configuration having two power strips (i.e., a first power strip and a second power strip of the at least one power strip), the electric motor may be electrically connected to the first power strip through a first electric motor connector and to the second power strip through a second electric motor connector. Each of the power strips may supply three-phase current. The electric motor can thus be designed as a six-phase electric motor. Therefore, the electric motor can be driven individually by the driving current supplied individually by either one or both of the two power supply boards. This provides a redundant and fault-insensitive design of the electronic control unit and the electric power steering system.

When the heat sink includes a protrusion protruding from the heat sink beyond the at least one power supply board, the protrusion may rest on an inner edge of an interior of a housing of the electric power steering system. This enables a defined position of the electronic control unit in the housing and a stable connection of the electronic control unit to the housing.

The electric power steering system may further include a torque sensor, a steering shaft, a handle (particularly a steering wheel), and a power source. The electric power steering system may further have an arrangement for operation of a car and may be arranged for operation of a car as described in the introductory part of the description.

Further advantages, features and details of the invention emerge from the following description, wherein embodiments of the invention are described in detail with reference to the figures illustrated in the following drawings. Thus, features from the claims as well as features mentioned in the description, taken alone or in any combination, may be essential to the invention.

Drawings

In the drawings, there are shown:

fig. 1 is an exploded illustration of a bottom side perspective view of an embodiment of an electronic control unit according to a first aspect of the present invention;

FIG. 2 is an exploded illustration of a top side perspective view of the electronic control unit of FIG. 1;

FIG. 3 is a detailed illustration of a side perspective view of two power and logic boards of the electronic control unit of FIGS. 1 and 2;

FIG. 4 is a detailed illustration of a side perspective view of the logic board and the connector board assembled together;

FIG. 5 is a detailed illustration of a side perspective view of the assembled logic board and connector board and the assembled first power board;

FIG. 6 is a detailed illustration of a side perspective view of a heat sink of the electronic control unit of FIGS. 1 and 2;

fig. 7 is a detailed illustration of a side perspective view of a process of assembling the heat sink of fig. 6 with the assembly of the logic board and the connector board and the first power board of fig. 5 assembled together;

FIG. 8 is a detailed illustration of a side perspective view of the assembly of the logic board and the connector board, the assembled first power board, and the heat sink of FIG. 6 assembled together;

fig. 9 is an illustration of a side perspective view of the electronic control unit 100 of fig. 1 and 2 in an assembled state;

FIG. 10 is an illustration of a side perspective view of a process of assembling the electronic control unit of FIG. 9 with an embodiment of the electric power steering system of the present invention; and

fig. 11 is a diagram of a section through the electric power steering system in which the electronic control unit is assembled inside of fig. 10.

Detailed Description

Fig. 1 shows an exploded illustration of a bottom side perspective view of an electronic control unit 100 according to an embodiment of the present invention. From this bottom side perspective, the bottom sides of the components of the electronic control unit 100 are visually illustrated.

Fig. 2 shows the electronic control unit 100 of fig. 1, with the difference that fig. 2 is from a top side perspective view. From this top side perspective, the top side of the components of the electronic control unit 100 are visibly illustrated.

As can be seen from fig. 1 and 2, the electronic control unit 100 includes two

power supply boards

30, 40, namely a first power supply board 30 and a second power supply board 40. The power strips 30, 40 may also be referred to as power stages. The two

power strips

30, 40 are arranged to supply drive current to an electric motor (not shown) of the electric power steering system 200 (see fig. 10 and 11). To this end, the first power strip 30 is connected to a first electric motor connector 80 that can be electrically connected to an electric motor. Further, to this end, the second power supply board 40 is connected to a second electric motor connector 90 that is electrically connectable with an electric motor.

Further, the electronic control unit 100 comprises a connector board 10. The connector board 10 comprises a plurality of (in this particular embodiment, three) plug connectors 11.1, 11.2, 11.3. In this particular embodiment, the first plug connector 11.1 and the second plug connector 11.2 are provided with electrical contacts (not shown) inside them. The electrical contacts may be made of, for example, a copper alloy to allow good electrical conductivity. These electrical contacts are arranged as a first signal connector 15.1 and a second signal connector 15.2. Said signal connectors 15.1, 15.2 extend from the plug connectors 11.1, 11.2 on the top side of the connector plate 10 to the bottom side of the connector plate 10.

The electronic control unit 100 also comprises a logic board 20. The logic board 20 is arranged to control the two

power supply boards

30, 40, or in other words, to control the operation of the electronic control unit 100, or in still other words, to control the transmission of the drive current to the electric motor. For this purpose, the signal connectors 15.1, 15.2 are connected to the logic board 20. Further, the logic board 20 is connected to the first power supply board 30 via the first logic connector 70. Further, the logic board 20 is connected to the second power supply board 40 via a second logic connector 60.

A signal plug (not shown) may be attached to the plug connectors 11.1, 11.2 for supplying signals from a sensor, such as a torque sensor, or other unit, such as another electronic control unit of a transportation device (not shown), such as a car, to the logic board 20. By means of said signals, such as the torque detected by the torque sensor or the travelling speed of the transport equipment, the logic board 20 can control the drive current via the two

power supply boards

30, 40.

The connector board 10 further comprises a third plug connector 11.3. The third plug connector 11.3 comprises further electrical contacts inside. These electrical contacts are arranged as a first power connector 16.1, 16.2 and a second power connector 17.1, 17.2. The second power connectors 17.1, 17.2 are longer than the first power connectors 16.1, 16.2 so that they can be connected with their

respective power boards

30, 40 at a respective distance from the connector board 10. In this embodiment, the first power connector 16.1, 16.2 and the second power connector 17.1, 17.2 are provided as metal strips.

A power plug (not shown) may be connected to the third plug connector 11.3 to provide power to the first power connector 16.1, 16.2 and the second power connector 17.1, 17.2. The power plug may be attached to a power source such as a battery (not shown) of the transportation device. The power supply is arranged as a three-phase power supply. The connector board 10 may also be referred to as a power and logic connector board as it provides power connections as well as logic or signal processing connections to the

respective boards

20, 30, 40 of the electronic control unit 100.

The first power connectors 16.1, 16.2 are connected to the second power board 40 and the second power connectors 17.1, 17.2 are connected to the first power board 30. Thereby, the first power supply board 30 is supplied with a three-phase current, and the second power supply board 40 is supplied with a three-phase current. The electronic control unit 100 is thus provided with six phases, and the electric motor may be provided as a six-phase electric motor. When one of the two

power supply boards

30, 40 malfunctions due to an error, the other power supply board can ensure safe and reliable operation of the electric motor by transmitting the driving current to the electric motor. Thus, it is prevented that a mistake in one of the

power supply boards

30, 40 results in an undesired loss of the steering function and possibly in accidents and injuries to the driver and passengers of the transport appliance.

As can be further seen from fig. 1 and 2, a heat sink 50 is arranged between the first power strip 30 and the second power strip 40. The heat sink 50 is thus sandwiched between the two

power supply boards

30, 40. In this embodiment, the heat sink 50 is provided as die-cast aluminum. The heat sink 50 enables dissipation of heat generated in the two

power supply boards

30, 40. For this reason, the radiator 50 is connected to a housing 210 of the electric power steering system 200, which will be explained in more detail later.

Furthermore, the connector plate 10 comprises a ventilation opening 13 and a ventilation element (not shown) for closing the ventilation opening 13. When the electronic control unit 100 is inserted into the housing 210 (which will also be explained in more detail later), the venting element provides pressure compensation to the interior of the housing 210 by the environment. Further, the connector board 10 comprises a seal 12. In this particular embodiment, the seal 12 is made of silicone rubber. When the electronic control unit 100 is inserted into the housing 210, the seal 12 seals the electronic control unit 100 from the environment inside the housing 210.

Fig. 3 shows the logic board 20, the first power board 30 and the second power board 40 in more detail in an exploded view. The logic board 20 comprises a first electronic component 21, wherein the first electronic components 21.1, 21.2, 21.3 are named by way of example. Further, the first power strip 30 comprises a second electronic component 31, wherein the second electronic components 31.1, 31.2, 31.3 are exemplarily named. Furthermore, the second power strip 40 comprises a third electronic component 41, wherein the third electronic components 31.1, 31.2, 31.3 are exemplarily named.

The first electronic component 21 may be a coil, a capacitor, at least one computing unit, such as a processor, and other electronic components for enabling computing operations based on the received signals and logical communication of the logic board 20 with the two

power supply boards

30, 40. The second and third electronic components 31, 41 may be coils, capacitors and other electronic components for enabling the respective

power supply board

30, 40 to transfer power from a power supply to the electric motor, as will be explained further later.

The logic board 20, the first power board 30, and the second power board 40 are shown in an orientation having their respective top and bottom sides, such as they are disposed within the electronic control unit 100. Thus, the largest of the second electronic components 31.1, 31.2, 31.3 on the bottom side of the first power strip 30 is shown towards the largest of the third electronic components 41.1, 41.2, 41.3 of the second power strip 40. These large electronic components 31, 41 generate a large amount of heat, and by virtue of this arrangement, the heat sink 50 can receive the second and third electronic components 31, 41 to enable good heat conduction characteristics to be obtained in order to effectively remove heat from the two

power supply boards

30, 40 via the heat sink 50 and the housing 210.

Further, the first power strip 30 comprises first power strip recesses 32.1, 32.2 for guiding the second power connectors 16.1, 16.2 therethrough. In addition, the first power strip 30 comprises power strip through holes 33.1, 33.2, 33.3 for guiding bolts 1 therethrough for fastening the heat sink 50 to the connector plate 10. These features will be explained in more detail later.

Fig. 4 shows the assembly of the logic board 20 and the connector board 10. The first signal connector 15.1 and the second signal connector 15.2 are connected to the logic board 20. In particular, the first and second signal connectors 15.1, 15.2 comprise a plurality of pins attached to corresponding pin receiving holes in the logic board 20.

The logic board 20 comprises two

logic connectors

60, 70 connected thereto with the purpose of enabling communication and control of the two

power supply boards

30, 40 by the logic board 20. Thus, each of the two

logical connectors

60, 70, i.e. the first logical connector 70 and the second logical connector 60, comprises a plurality of electrical connector pins (not noted). The electrical connector pins of the first logic connector 70 are relatively shorter than the electrical connector pins of the second logic connector 60. The reason is that the first logic connector 70 connects the logic board 20 and the first power supply board 30, wherein the distance between the logic board 20 and the first power supply board 30 is relatively short in the assembled state of the electronic control unit 100. However, the distance between the logic board 20 and the second power supply board 40 connected by the second logic connector 60 is relatively long because the first power supply board 30 and the heat sink 50 are arranged therebetween, as can be seen in an assembled state of the electronic control unit 100 of fig. 10, for example.

The electrical connector pins are inserted into corresponding connector pin holes (not labeled) in the interior of the logic board 20. Connector pin holes for respective electrical connector pins are arranged at two opposite ends of the logic board 20. Thereby, the first logic connector 70 and the second logic connector 60 are arranged at two opposite ends of the logic board 20. Further, the logic board 20 includes connection pin holes (not labeled) for corresponding first connection pins (not labeled) of the first logic connector 70 and connection pin holes for corresponding second connection pins (not labeled) of the second logic connector 60. By means of the connection pins, the two

logic connectors

60, 70 are firmly secured in the logic board 20.

The electrical connector pins are arranged in the

logic connector housings

71, 61 of the first logic connector 70 and the second logic connector 60. In this particular embodiment, the second logic connector housing 61 is comprised of two separate pieces. This design may be chosen due to the long extension of the electrical connector pins. The first portion of the second logic connector housing 61 includes connection pins for corresponding connection pin holes of the logic board 20, and the second portion of the second logic connector housing 61 includes connection pins for being fixed in corresponding connection pin holes of the second power supply board 40. Further, the first logic connector housing 71 includes connection pins for being fixed in corresponding connection pin holes of the first power supply board 30.

As can be seen from this figure, the logic board 20 comprises at its edges cutouts for ridges 18.1, 18.2, 18.3, said ridges 18.1, 18.2, 18.3 protruding from the connector board 10 towards the logic board 20 and beyond the logic board. These elevations 18.2, 18.3 enable fastening of the heat sink 50 with the connector board 10 and thereby sandwiching the logic board 20 and the first power supply board 30 between the heat sink 50 and the connector board 10 as will be explained later. The elevations 18.2, 18.3 may be provided with moulded holes in the interior. The moulded hole may have a preformed thread for the bolt 1 or be threaded by a self-tapping bolt or screw 1.

The first power connectors 17.1, 17.2 extend from the connector board 10 through cutouts (not labeled) at the edge of the logic board 20 towards the first power board 30. Further, second power connectors 16.1, 16.2 extend from the connector board 10 towards the second power board 40 close to the logic board 20 and the first power connectors 17.1, 17.2.

Fig. 5 shows the assembly of the first power board 30 with the logic board 20 and the connector board 10.

The first electric motor connector 80 comprises three first electric phase pins 82.1, 82.2, 82.3 for electrical connection with an electric motor of the electric power steering system 200. The three first electrical phase pins 82.1, 82.2, 82.3 are received in the first electric motor connector housing 81. The first electric motor connector housing 81 includes connection pins (not labeled) for connection with corresponding connection pin holes (not labeled) in the first power strip 30. Further, the three first electrical phase pins 82.1, 82.2, 82.3 comprise a plurality of first power strip connection pins (not shown) for electrical connection with the first power strip 30 at an end opposite to an end for connection with corresponding electrical motor pins (not shown) of the electrical motor.

The first logic connector 70 is connected to the first power board 30. Further, the second power connectors 16.1, 16.2 are guided through the first power strip recesses 32.1, 32.2 of the first power strip 30.

The first electric motor connector 80 is arranged next to the second logic connector 60 so that they can extend together along the heat sink cut-out 53 as shown in the heat sink 50 of fig. 6. The first electronic component 31 of the first power supply board 30 extends toward the heat sink 50 to be arranged on the top side of the first power supply board 30.

Fig. 6 shows the heat sink 50 in more detail from the bottom side of the heat sink 50. The heat sink 50 has a heat sink edge 59 that surrounds the heat sink 50. The heat sink 50, in particular the heat sink rim 59, comprises a slot 51 for crimping the housing 210 of the electric power steering system 200 into the slot 51. Thereby, the housing 210 is mechanically fixed to the heat sink 50 and finally to the electronic control unit 100. Further, the heat sink 50 is thermally connected to the housing 210 such that heat generated by the two

power strips

30, 40 can be dissipated via the heat sink 50 along the housing 210, said housing 210 having a much larger surface area for dissipation. Furthermore, the surface area of the housing 210 may be thermally connected to the environment, so that the housing 210 is cooled or, in other words, may exchange heat with the environment.

The groove 51 is a peripheral groove 51 such that it is disposed around the periphery of the heat sink rim 59. The heat sink rim 59 further comprises two peripheral outer surfaces 58.1, 58.2, said peripheral groove 51 being arranged between said peripheral outer surfaces 58.1, 58.2. The two peripheral outer surfaces 58.1, 58.2 of the heat sink rim 59 are configured to contact the inner surface 211 of the housing 210, as can be seen from fig. 17. To this end, the outer diameter of the peripheral outer surfaces 58.1, 58.2 is equal or substantially equal to the inner diameter of the inner surface 211 of the housing 210.

The structure of the heat sink 50 will be further explained below with reference to fig. 7 and 8, fig. 7 showing a process of assembling the heat sink 50 with the first power supply board 30 assembled with the logic board 20 and the connector board 10, and fig. 8 showing the assembly according to the process of fig. 7. Fig. 7 and 8 show the top side of the heat sink 50, while fig. 6 shows the bottom side of the heat sink 50.

The heat sink 50 is configured as a circular heat sink plate, wherein the heat sink 50 comprises a heat sink cut-out 53. The heat sink cutout 53 extends from the heat sink edge 59 to the interior of the heat sink 50. The second logic connector 60 and the first electric motor connector 80 extend through the heat sink cut-out 53 in an assembled state in which the heat sink 50 is attached to the first power strip 30, as can be seen in fig. 9.

Further, the heat sink 50 comprises on its bottom and top sides several heat conducting surfaces 52 for attaching said heat conducting surfaces 52 to the first and second

power supply boards

30, 40, in particular the first and second electronic components 31, 41, by means of a thermal interface material (not shown). In fig. 6 and 8, the heat-conducting surfaces 52.1, 52.2 on the bottom side and the heat-conducting surface 52.3 on the top side are exemplarily marked. In the assembled state of fig. 8, the first electronic component 31 of the first power strip 30 is in direct contact with the heat conducting surfaces 52.1, 52.2 on the bottom side of the heat sink 50 via a thermal interface material. The heat conducting surfaces 52.1, 52.2 of the bottom side are arranged at different heights along the thickness of the heat sink 50 and may thereby be adapted or attached to first electronic components 31 of different sizes or heights. The same may apply to the top side, so that the heat conducting surface 52 of the top side of the heat sink 50 may be arranged at different heights along the thickness of the heat sink 50. Thereby, the first electronic component 31 efficiently transfers heat to the heat sink 50.

Furthermore, the heat sink 50 comprises heat sink through holes 54.1, 54.2, 54.3, as can be seen from the bottom side in fig. 10 and from the top side in fig. 11. The first power supply board 30 is fixed by means of bolts 1 which pass through the heat sink through holes 54 and are fastened in the bulges 18.1, 18.2 of the connector board 10. The bolt 1 further passes through the power supply plate through holes 33.1, 33.2, 33.3 of the first power supply plate 30, as shown in the figure.

Furthermore, the heat sink 50 comprises a heat sink recess 55 for guiding the second power connectors 16.1, 16.2 of the connector board 10 therethrough. This enables the second power connector 16.1, 16.2 to be connected to the second power strip 40 when the heat sink 50 is attached to the first power strip 30.

Furthermore, the heat sink 50 comprises heat sink protrusions 57.1, 57.2, 57.3 which protrude from the heat sink 50 in the assembled state of the electronic control unit 100 beyond the two

power supply boards

30, 40, as can be seen in fig. 10. These radiator projections 57.1, 57.2 may be arranged to rest on an inner rim 212 inside the housing 210 of the electric power steering system 200.

The heat sink 50 also comprises heat sink holes 56.1, 56.2, 56.3 on its top side. The second power strip 40 can be fastened to the heat sink 50 by means of the bolts 1 in the heat sink holes 56.1, 56.2, 56.3. The radiator holes 56.1, 56.2, 56.3 may be pre-threaded or threaded by self-tapping bolts or screws 1.

Fig. 9 shows the electronic control unit 100 in an assembled state. The second power strip 40 is attached to the heat conducting surface 52 of the top side of the heat sink 50 by the second electronic component 41 on the bottom side. The second electric motor connector 90 comprises three second electrical phase pins 92.1, 92.2, 92.3 arranged in a second electric motor connector housing 91. The second electric motor connector housing 91 comprises further connection pins for connection with the sixth connection pin holes in the second power strip 40.

Further, the three second electrical phase pins 92.1, 92.2, 92.3 comprise several second power strip connection pins for electrical connection with the second power strip 40 at an end opposite to the end for connection with a corresponding electrical motor pin (not shown) of the electrical motor. Further, the second electric motor connector housing 91 comprises a second electric motor connector housing through hole for guiding the bolt 1 therethrough for connecting the second power supply board 40 to the heat sink holes 56.1, 56.3 of the heat sink 50 through the second electric motor connector housing 91.

Further bolts 1 are guided through corresponding through holes in the second power supply plate 40 to connect to the heat sink holes 56.2, 56.4 of the heat sink 50. Here, the second power supply board 40 is attached with its bottom side to the top side of the heat sink 50. The second power strip 40 further comprises second power strip recesses 42.1, 42.2, 42.3 through which the first electrical phase pins 82.1, 82.2, 82.3 of the first electric motor connector 80 are guided.

All bolts 1 are fastened so that the second power supply plate 40 is fastened to the heat sink 50 and the heat sink 50 is fastened to the connector plate 10. The heat sink 50 is thus sandwiched between the first power-supply board 30 and the second power-supply board 40. The logic board 20 is sandwiched between the first power supply board 30 and the heat sink 50. The electrical phase pins 82.1, 82.2, 82.3, 92.1, 92.2, 92.3 extend out of the second power strip 40 and in particular out of the heat sink projections 57.1, 57.2, 57.3, so that they can be connected with the electric motor pins of the electric motor. After the electronic control unit 100 is inserted into the housing 210, a venting element may be inserted into the venting opening 13.

Fig. 10 illustrates a process of inserting the electronic control unit 100 into the housing 210 of the electric power steering system 200. The heat sink projections 57.1, 57.2, 57.3 act as guides during this process.

Fig. 11 shows a cross section through a portion of an electric power steering system 200 having a housing 210. Wherein the housing 210 has not yet been crimped into the slot 51 of the heat sink 50. However, the crimping operation is indicated by an arrow marked by the direction of the force F by the crimping operation. Thereby, the case 210 is plastically deformed and extends into the groove 51 of the heat sink 50. The heat sink 50 and the housing 210 thereby become attached to and thermally coupled to each other.

Further, the peripheral outer surfaces 58.1, 58.2 of the heat sink 50 are attached to the inner surface 211 of the housing 210 for thermal coupling and enabling the heat sink 50 to dissipate heat generated by the two

power supply boards

30, 40 attached to the heat sink 50 to the environment through the housing 210. Furthermore, the heat sink protrusions 58.1, 58.2, 58.3 may be arranged to rest on the inner rim 212 inside the housing 210.

The housing 210 is further sealed by a peripheral seal 12 of the connector plate 10 of the electronic control unit 100 against an inner surface 211 of the housing 210. The connector board 10 is thus designed as a cap of the housing 210. Further, as can be seen in this cross section, the first electrical phase pins 82.1, 82.2, 82.3 will be electrically connected to the electric motor pins of the electric motor of the electric power steering system 200.

List of reference numerals

10 connector board

11 plug connector

12 seal

13 vent opening

15 signal connector

16 second power connector

17 first power connector

18 raised portion

20 logic board

21 first electronic component

30 first power supply board

31 second electronic component

32 first power supply board groove

33 Power strip through hole

40 second Power strip

41 third electronic component

42 second power panel groove

50 radiator

51 groove

52 thermally conductive surface

53 radiator cut

54 radiator through hole

55 radiator groove

56 radiator hole

57 Heat sink projection

58 peripheral outer surface

59 heat sink edge

60 second logical connector

61 second logic connector housing

70 first logical connector

71 first logic connector housing

80 first electric motor connector

81 first electric motor connector housing

82 first electrical phase pin

90 second electric motor connector

91 second electric motor connector housing

92 second electrical phase pin

100 electronic control unit

200 electric power steering system

210 casing

211 inner surface

212 inner edge

Force F

Claims

1. An electronic control unit (100) for an electric power steering system (200), the electric power steering system (200) comprising a housing (210) and an electric motor, the electronic control unit (100) being configured to be arranged inside the housing (210) and electrically connected to the electric motor, whereby the electronic control unit (100) comprises at least one power supply board (30, 40) and a heat sink (50), the at least one power supply board (30, 40) being attached to the heat sink (50) and whereby at least one peripheral outer surface (58.1, 58.2) of a heat sink edge (59) of the heat sink (50) is in direct contact with an inner surface (211) of the housing (210) such that heat generated by the at least one power supply board (30, 40) is conducted to the housing (210) via the heat sink (50).

2. Electronic control unit (100) according to claim 1, characterized in that the heat sink (50) comprises a slot (51) arranged for crimping the housing (210) into the slot (51) and thereby fixing the heat sink (50) and the housing (210) together.

3. The electronic control unit (100) according to claim 2, characterized in that the groove (51) is a peripheral groove (51) such that it is arranged around at least half of the periphery of the radiator edge (59) of the radiator (50), preferably around the entire periphery of the radiator (50).

4. Electronic control unit (100) according to claim 2 or 3, characterized in that the groove (51) is arranged between two peripheral outer surfaces (58.1, 58.2) of the heat sink rim (59), which are in direct contact with an inner surface (211) of the housing (210).

5. The electronic control unit (100) according to any one of claims 2 to 4, characterized in that the housing (210) subjected to crimping thermally connects the heat sink (50) with the housing (210) at the slot (51).

6. The electronic control unit (100) according to any one of the preceding claims, characterised in that the electronic control unit (100) comprises as the at least one power strip (30, 40) a first power strip (30) and a second power strip (40), the heat sink (50) being sandwiched between the first power strip (30) and the second power strip (40).

7. Electronic control unit (100) according to claim 6, characterized in that the electronic components (31, 41) of the first power strip (30) and of the second power strip (40) face the heat sink (50).

8. Electronic control unit (100) according to any one of the preceding claims, wherein the heat sink (50) is configured as an at least partially circular heat sink plate.

9. Electronic control unit (100) according to any of the preceding claims, characterized in that the heat sink (50) comprises several heat conducting surfaces (52) arranged in contact with electronic components (31, 41) of the at least one power strip (30, 40).

10. The electronic control unit (100) of claim 8, wherein the number of thermally conductive surfaces (52) are arranged at different heights along the thickness of the heat sink (50) to accommodate electronic components (31, 41) of different heights.

11. Electronic control unit (100) according to any of the preceding claims, characterized in that the heat sink (50) comprises a heat sink through hole (54) and at least one power board (30) of the at least one power board (30, 40) is fixed to the heat sink (50) by a bolt (1) passing through the heat sink through hole (54) and being fastened in a boss (18) extending from a connector board (10) of the electronic control unit (100).

12. Electronic control unit (100) according to any of the preceding claims, wherein the heat sink (50) comprises a heat sink hole (56) and at least one power strip (40) of the at least one power strip (30, 40) is fixed to the heat sink (50) by means of a bolt (1) fastened in the heat sink hole (56).

13. Electronic control unit (100) according to any of the preceding claims, wherein the heat sink (50) comprises a heat sink recess (55) for a second power connector (16) of the electronic control unit (100), the second power connector (16) extending from a connector board (10) of the electronic control unit (100) through the heat sink recess (55) inside the heat sink (50) to at least one power board (40) of the at least one power board (30, 40).

14. Electronic control unit (100) according to any one of the preceding claims, characterized in that the heat sink (50) comprises a heat sink cut-out (53) extending in particular from the heat sink edge (59) to the interior of the heat sink (50), a second logic connector (60) extending from a logic board (20) of the electronic control unit (100) through the heat sink cut-out (53) to at least one power board (40) of the at least one power board (30, 40).

15. An electric power steering system (200) comprising an electronic control unit (100) according to any of the preceding claims, characterized in that the electric motor of the electric power steering system (200) is electrically connected to the at least one power supply board (30, 40) by means of at least one electric motor connector (80, 90), and whereby the housing (210) of the electric power steering system (200) is crimped into a slot (51) of a heat sink (50) of the electronic control unit (100).